📝 SummarXiv

Abstract

Since the earliest electroencephalography experiments, large scale oscillations have been observed in the mammalian brain. More recently, episodes of oscillation and bursting have been identified not only in the cerebral cortex and thalamus, but pervasively in the healthy basal ganglia. The basal ganglia mediated synchronization model, introduced here, implicates these episodes in the integration of stimulus-response and reinforcement mechanisms in the basal ganglia with cortical association mechanisms. In so doing, the model helps explain how oscillations and synchrony are functionally central, and in particular, how they organize neural activity to exploit the selectivity of coincidence detectors in cortex and beyond. In the core mechanism of the model, salient spatiotemporal activity patterns in cortex are selectively focused by and routed through the basal ganglia to the thalamus. Coherent thalamocortical activity patterns then project back to widely separated areas of cortex, where they establish and facilitate contextually appropriate functional connections, while disconnecting and inhibiting competing ones. Corticostriatal, striatopallidal, and striatonigral conduction delays are crucial to this mechanism. These delays are unusually long, and unusually varied, in arrangements that facilitate learning of useful time alignments and associated resonant frequencies. Other structural arrangements in the basal ganglia show further specialization for this role, with convergence in the inputs from cortex, and divergence in many of the return paths to cortex, that systematically reflect corticocortical anatomical connectivity. The basal ganglia also target the dopaminergic, cholinergic, and serotonergic centers of the brainstem and basal forebrain, and the intralaminar and reticular nuclei of the thalamus, structures broadly implicated in the modulation of network activity and [...]